Research on marine and freshwater fishes
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Most of the fish research at SEAFDEC AQD in 1992-1994 was on milkfish. Studies were conducted on year-round spawning through hormonal or environmental manipulation; optimum lipid and protein levels and ration size for captive broodstock; and the influence of spawner age on reproductive performance. The economics of hatchery operations, alone or integrated with broodstock as a commercial enterprise, was assessed. Mass production of larvae was refined with the use of commercial or SEAFDEC-formulated larval diets. Alternative rearing schemes in large tanks and ponds were tried. Hatcheryproduced and wild-caught larvae were compared in terms of growth and production in experimental nursery and grow-out ponds. Supplemental diets for brackishwater grow-out culture were formulated. Studies on broodstock management of grouper Epinephelus spp. included lipid enrichment of the diet and hormonal induction of sex inversion. Seed production techniques were developed but survival rates were low. Grouper culture was found economically feasible in experimental ponds with 'trash' fish as feed. The mangrove red snapper Lutjanus argentimaculatus was successfully induced to spawn with injection of human chorionic gonadotropin. Initial larval rearing trials were successful but survival rates must be improved. Hormonal manipulation of spawning of the Asian sea bass Lates calcarifer allows seed production during most of the year. Photoperiod manipulation leads to maturation of females, but not males, beyond the natural breeding season (April-November). Nursery rearing of 9 mm juveniles is feasible in floating net cages with night lights that attract food zooplankton. The requirements of sea bass for lipid, protein, carbohydrates, and essential amino acids were determined. In the rabbitfish Siganus guttatus, weekly injections of luteinizing hormone releasing hormone analogue (LHRHa) sustains milt production for three weeks. Thyroid hormones injected into broodstocks improved the growth of larvae to day 7. Induced spawning techniques for the Asian catfish Clarias macrocephalus were refined by determining the seasonal responsiveness to LHRHa and pimozide injections and testing for pheromonal induction of spontaneous spawning. The optimum insemination rate was determined and egg hatchability was enhanced by removal of the adhesive coat before incubation. Several practical diets for catfish during grow-out culture were tested against 'trash' fish. The broodstock management for bighead carp Aristichthys nobilis was studied. Cage-reared juveniles from cage-reared broodstock showed the best growth. To improve the reproductive performance, the broodstock diets were supplemented with vitamins A, C, and E. Research on tilapias focused on genetics and strain selection. Several strain testing procedures for Nile tilapia were evaluated in their efficiency to detect economically important strain differences. Reference lines were developed from two existing red tilapia strains to measure and reduce the effects of uncontrolled nongenetic variables in strain evaluation experiments with Nile tilapia. The tolerance of two Nile tilapia strains to heavy metals was similar when gauged by the 24-hour and 96-hour lethal concentration and by fish growth, survival, and reproductive performance. In a separate study, four strains of red tilapia showed generally higher seed production when reared in tanks than in cages. Improvements in the feed and feeding management for Nile tilapia were also studied. Intensive tilapia farming and feeding have led to oxygen depletion and fish kills in Sampaloc Lake. To rehabilitate the lake, it is imperative to reduce the farming area from 30 to 6 hectares; stop the use of commercial feeds; and remove the water hyacinths and other debris. Fish kills in Laguna de Bay have also become serious in recent years, and a review of the occurrences, losses, and possible causes is currently being conducted. Studies on the epizootic ulcerative syndrome of snakeheads in Laguna de Bay have yet to pinpoint the pathogen. Skin lesions in tilapias in several ponds and lakes in the country were found to be due to bacteria.
Emata, A. C. 1995. Research on marine and freshwater fishes, pp. 167-186. In: Bagarinao TU, Flores EEC (eds) Towards Sustainable Aquaculture in Southeast Asia and Japan. SEAFDEC Aquaculture Department, Iloilo, Philippines.
PublisherAquaculture Department, Southeast Asian Fisheries Development Center
Water quality; Environmental factors; Hormones; Ponds; Hybridization; Feed composition; Marine fish; Ecology; Genetics; Lakes; Growth regulators; Research; Brackishwater fish; Brood stocks; Fish culture; Diets; Animal nutrition; Growth rate; Seed (aquaculture); Feed; Pond culture; Seed production; Strains; Aquaculture economics; Fish diseases; Hybrid culture; Cage culture; Prophylaxis; Feeding experiments; Gonads; Marine aquaculture; Reproduction; Freshwater aquaculture; Pisces; Dicentrarchus labrax; Clarias macrocephalus; Chanos chanos; Epinephelus; Epinephelus suillus; Aristichthys nobilis; Lutjanus argentimaculatus; Siganus guttatus; Lates calcarifer; Epinephelus coioides; Oreochromis niloticus; Giant perch; Golden rabbitfish; Mangrove jack; Milkfish; Philippines; South East Asia; Philippines, Luzon I., Zambales, Sampaloc L.; Philippines, Luzon I., Laguna de Bay
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Conference paperPC Liong, HB Hanafi, ZO Merican & G Nagaraj - In JV Juario & LV Benitez (Eds.), Seminar on Aquaculture Development in Southeast Asia, 8-12 September 1987, Iloilo City, Philippines, 1988 - Aquaculture Department, Southeast Asian Fisheries Development CenterMalaysia is a fish-consuming country with fish representing 60% of a total animal protein intake. At an annual per capita consumption of 32 kg some 560 000 mt of fish is required for the projected of 17.5 million people in year 2000. Coastal marine capture fisheries, the mainstay of Malaysia's fishsupply, has not shown any increase in landings over the last few years. In fact in 1985 there was a decline of 3.7% compared to 1984 fish landings. This declining contribution of marine fisheries is compensated by an increase in aquaculture production. In 1985, aquaculture contributed 51 709 mt to the total fish supply. This represents 10% of the total fish landings of 514 570 mt or 13% of total table (edible) fish landings. Malaysia does not have a long standing aquaculture tradition unlike its neighbours in the Indo-Pacific. Even then, the industry has seen rapid growth in the last few years. Today there are 19 species of finfishes, crustaceans and shellfish cultured in the country. The main freshwater fish species bred and cultured are bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), Indonesian carp (Punctius gonionotus), catfish (Clarias macrocephalus and Pangasius spp), snakefish gourami (Trichogaster pectoralis) and tilapia (mainly Oreochromis niloticus). Marine finfishes bred and cultured are sea bass (Lates calcarifer), grouper (Epinephelus sp.) and snapper (Lutjanus johni). Penaeus monodon is the dominant marine prawn species bred and cultured but culture of P. merguiensis is receiving considerable interest. Macrobrachium rosenbergii is the only freshwater prawn cultured commercially. Molluscs cultured are the blood clam (Anadara granosa) and the green mussel (Perna viridis). In 1985, blood clam and mussel culture accounted for 87% of all aquaculture production of Malaysia, freshwater fish 12%, floating cage culture of marine fish 0.7% and brackishwater pond culture 0.3%. In terms of value blood clam and mussels represented 30% (M$15M) of total value (M$49.5M), freshwater fish 57% (M$28M),cage culture of marine fin fishes 7% (M$3.4M),and brackishwater pond production 6% (M$2.1M). Aquaculture in Malaysia has considerable growth potential. It is projected that 22 000 ha of mangrove will be opened by the year 2000 for shrimp culture. Some 330 000 m2 of protected coastal waters have been identified for cage culture. Some 6500 rafts can considerably expand the present capacity. In freshwater culture about 8000 ha of land and 17 500 ha of mining pools can be developed while 200 000 ha of artificial lakes and impoundments for freshwater fish cage culture are available. Yet such development is not without constraints. Freshwater finfish culture is hampered by lack of good quality broodstock. There is also a limited market for freshwater finfishes. Marine finfish culture is limited by lack of fingerlings and good quality compounded diet to replace trash fish which is deteriorating in quality and quantity. Marine prawn culture is heavily dependent on wild spawners, the supply unpredictable and inadequate. Acid sulfate soil continues to cause the deterioration of brackishwater ponds. Cockles and mussels can be sold to export markets only if they meet specific quality standards.
Conference paperMR Catacutan - In MR Catacutan, RM Coloso & BO Acosta (Eds.), Development and Use of Alternative Dietary Ingredients or Fish Meal Substitutes in Aquaculture Feed Formulation … Ingredients or Fish Meal Substitutes in Aquaculture Feed Formulation, 9-11 December 2014, Nay Pyi Taw, Myanmar, 2015 - Aquaculture Department, Southeast Asian Fisheries Development CenterCultured marine aquatic species are predominantly carnivorous. Major species in the region are seabass, grouper, snapper, tiger shrimp, mangrove crab and abalone. These species, except for abalone, require a high level of dietary protein mostly supplied by marine sources such as fish meal. Global production of marine fish and marine shrimps showed a 3-4 fold increase from 1995 to 2010. For the same period, the usage of commercial feed for production of marine fish and shrimps increased while the fish meal portion in the formulation decreased. This is indicative of fish meal being substituted with alternative sources in commercial feed production, and to some extent the substitution of marine oil which particularly improved the FCR for the marine fish production from 2.0 to 1.9 and for marine shrimps from 2.0 to 1.6. Plant products that include cereal grains, legumes and oilseeds have the most potential among the alternative ingredients for use in aquafeed. The use of these resources for high value marine species is limited due to a variety of anti-nutritional substances they contain. Removal of these substances by processing techniques has improved utilization but with added cost. Hence, fish meal is still the primary source of protein for marine carnivores and its substitution with higher amounts of alternative plant proteins may be difficult compared with lower levels of replacements. The Asian region has accounted for the more than 50% of the total global aquaculture production in 2012 with indications of increased utilization of alternative protein sources in commercial feed production. For the major marine species in the region the increasing trend of plant protein usage with the targeted levels of substitution of fish meal with plant protein sources should be sustainable.
ArticleGF Quinitio, JD Tan-Fermin & A Nagai -
Fisheries Science, 2001 - Japanese Society of Fisheries ScienceThirty immature juvenile grouper Epinephelus coioides (19-168 g bodyweight, BW) were randomly stocked in four units 6 t tanks to determine if mibolerone can be used to induce sex inversion in groupers. After acclimatization and weaning to artificial feed, the feed given daily (4% BW/day) was supplemented with 0, 50, 100, and 200 μg mibolerone/kg feed for about 18 weeks. Thereafter, the hormone treatment was withdrawn and the experiment was terminated at Week 24. Ten fish were killed for gonad histology at stocking to serve as an initial control while about three to five fish were killed every 8 weeks. In general, ovaries of initial controls showed the presence of moderate stromal cells and gonia and few primary oocytes. At Weeks 8 and 16, ovaries of the control fish (0 μg/kg) were similar to that of the initial control except that primary oocytes increased at Week 24. Gonads of fish fed diets containing 100 and 200 μg/kg had none to moderate spermatocytes and few spermatids at Week 8 and 16, although spermatozoa were not observed, indicating that the fish were undergoing spermatogenesis. Spermatogenesis at 50 μg/kg was not as advanced since only few spermatocytes occurred at Weeks 8 followed by moderate gonia and no spermatocytes and spermatids at Week 16. However, the presence of few primary oocytes was observed when mibolerone was withdrawn suggesting that sex-inversed fish reverted back to a female condition. These results show that sex inversion in juvenile grouper can be induced by oral administration of mibolerone and may have possible application on mature females to produce functional males.